vanDivX<br /><br />As the weights are rotating, the central shaft will move to and fro, such that the center of mass of the system will remain in the same location. When the balls are both travelling North, the shaft will be moving South. When you lock the shafts, all motion will cease, and the device will remain at its original location. <br /><br />If you had someone standing on the Earth, holding the central shaft so that it would not wobble, and then froze the rotation when both weights were heading in the same direction. and then let go, yes, it would fly off into space. <div class="Discussion_UserSignature"> <p> </p><p> </p> </div>